Apparatus for electroplating



April 17, 1956 J. J. sHANLEY 2,742,417

APPARATUS FOR ELECTROPLATING Filed Nov. 20, 1950 5 Sheets-Sheet 1 mIN oJ of oJ o J IN V EN TOR.

www

Hlm .WH

April 17, 1956 J. J. sHANLEY APPARATUS FOR ELECTROPLATING Filed Nov. 20, 1950 5 Sheets-Sheet 2 INVENTOR.

5 Sheets-Sheet 3 Filed Nov. 20, 1950 nlllll.

INVENTOR.

United States Patent O APPARATUS FOR ELECTROPLATIN G James J. Shanley, Washington, D. C., assigner to National Steel Corporation, a corporation of Delaware Application November 20, 1950, Serial No. 196,575

2 Claims. (Cl. 204-211) The present invention relates to improvements in apparatus for progressively electroplating a continuously moving strip of material, for example, a strip of black plate, with a coating of protective metal, such as tin, zinc or the like.

When electroplating elongated strip metal, the strip is continuously progressively moved longitudinally along a path across one or a series of electroplating cells disposed along the path. Each cell contains a bath of electroplating solution and an anode of soluble plating metal disposed in the bath. The position of the strip relative to the anode greatly influences the character of the coating deposited. One problem encountered in plating strip is causedby camber in the rolled strip, which as the strip is moved at a high speed along the path across the cells causes the stripto weave laterallyback and forth. This lateral weaving of the strip is very diihcult, if not impossible, to prevent. As a result, it is necessary to make the anode Wider than the theoreticalor loptimum width. The wider anode causes the deposition of a heavier coating along the edge of the .strip. This phenomenon is commonly referred to as edge effect. Besides wasting anode metal, the heavy coating along the edges of the strip is undesirable and theser edges must be sheared oi. Other operational diiculties also are, created. j

The commercial electroplating line usually has to plate successive lengths lof strip having dilerent Widths. Accordingly, it has been the customary practice to use an anode wide'enough for the widest strip to be plated. Asa result, the narrower lengths of strip are plated with ananode that isA too wide. This also causes excessive edge effect. In addition, a number of operational difficulties are created. When a wider rvanode is used for platingia narrower strip, more metal is' removed from theanode at the center portion than the edges so that the anode Yis deformed. VIf an'attempt is made later to platea wider strip with the same anode, the edges'of the anode are closer tothe strip and this in turn results in a non-uniform coating being deposited that is thinnerv f along--the center portion and heavier along the side portions. In order to overcome this diiculty, it is customary to schedule operations so that the wider strips are platedY irst This only partially answers the problem as the narrower strip is plated with an anode'of excessive Width.

Accordingly, it is an object of the present invention to provide an improved apparatus for electroplating strip that can electroplate successive lengths of strip yof the same and diierent widths and do this with an anode-of the correct width for each length.

Itis an object of the present invention to provide an improved apparatus 'for electroplating strip that will maintain the anode in alignment with strip whentthe strip weaves .back and forth laterally of the direction of strip travel. f

Itis ari-object of the present invention to provide an improved apparatus for electroplating strip that will ICC widths and simultaneously maintain the anode in alignment with any lengths of strip which laterally weave.

In accordance with my invention the apparatus for progressively electroplating continuously moving strip includes an electroplating cell containing an anode. The anode preferably comprises one or more elongated anode bars extending across from side to side of the strip. Power actuated means are provided for moving the anode bar to vary the width of the anode. Control means responsive to the strip width is provided to actuate the anode moving means to adjust the width of the anode in accordance with the width of the strip. The anode is supported for movement transversely of the direction of strip travel and is automatically maintained in alignment with the strip upon lateral weaving of the strip.

yThese and other objects and advantages of the present invention will become more readily apparent from the following detailed description, taken with the accompanying drawings, in which:

Figure l is a plan view of avportion of an electroplating line embodying the principles of the present invention;

Figure 2 is a longitudinal sectional view taken along line 2 2 of Figure l; Y

Figure 3 is a transverse sectional view taken along line 3 3 of Figure 2;

Figure 4 is a schematic plan view of the electroplating line of Figure l and illustrating transverse weaving of the strip;

Figure 5 is a plan view of a portion of the electroplating lineof Figure l and includes a diagrammatic representation of an electric circuit controlling operation of an electroplating cell;

Figure 6 is a fragmentary sectional view taken along line 6-6 of Figure 2;

Figure 7 is a view similar to Figure 6 illustrating a modification of the apparatus of Fig. 5; and,

Figure 8 is a diagrammatic view illustrating another embodiment of the present invention.

Referring to the drawings and more particularly to Figures 1 to 3 illustrating a portion of an electroplating system embodying the principles of the present invention, a strip S is continuously progressively moved along a path across a series of electroplating cells 10 with the bottom surface 12, the surface to be plated, in contact with an electrolytic bath in each cell. The bottom surface 12 of the strip S is moved across and in electrolytic relation with a soluble anode 11 submerged in the bath of electrolyte in the cell 10. They strip yS and anode y 11 are connected to a source of electroplating current as kthe cathode and anode, respectively, so that a layer of anode metalis deposited on the surface 12 which faces the anode.

The means for moving the strip S through the electro v A similar pair of rolls 15, 16 are mounted adjacent the exit end of the cell. Customarily, in an electroplating f line, a pair of these rolls are mounted between each pair of cells and at each end of the line so that there is a pair of rolls at each end of each cell. One roll of each pair, the upper rolls 13 and l5, is an electrically conduc-` tive contact roll for connecting the strip as a cathode to a source of electroplating current. As will be more fully hereinafter described, the contact roll 15 and the anode 11 are connected through a control circuit to the opposite sides of a source of electric current. The bottom yor lower rolls 14 and 16 are Vback-up rolls pressing the strip up against the corresponding or respective contact rolls Patented Apr. 17, 1956` 13 and 1550 that the contact rolls and the strip will have good electricalcontact with each other and so that each pair of rolls will securely grip the strip therebetween, The rolls 13 through 16 may be power driven by any suitable means, not shown, such as is. customarily used in steel mills for rotating the rolls which support and more a strip along a predetermined path.

The electroplating cells are identical and only one will be described in detail. Identical portions of the differ'- ent cells will be identified by the same reference numerals.

The cell includes a tank 1.8. positioned along the path of the strip S so that the strip passes across the tank 10 from end to end in contact with a bathV of electrolyte solution in the tank. As shown, the. tank 18 is disposed below the path of the strip and has side walls 19 located on opposite sides of the strip path that extend above the path of the strip toprevent or reduce spillage of the electrolyte. The anode 11 is arranged in electrolytic relationship to the path of the strip surface 12 and comprises a plurality of similar elongated anode elements or bars 20 supported in spaced apart parallel relationship.

The means for supporting the anodes 20 in spaced apart relationship includes a central member 21. A pin 22 is mounted in member 21 and in each anode bar Z13 to provide a pivotal connection therebetween. Each bar 20 is swingable about the vertical axis of pin 22, and the axes of all of the pins are located along a line extending parallel to the direction of strip travel. Each pin 22 is located substantially midway between the opposite ends of the respective anode bar. An electrically conductive member 23 extends parallel to member 21 and across the ends of. anode bars 20. Between the end of each bar 20 and member 23, there is a pin 24 which fits a recess in the bar and a recess in the member to provide therebetween a pivotal connection. The pivotal connections at the ends of the bars are located along a line parallel to the direction of strip travel and parallel to the line along which the axes of pins 22 are located. Member 23 is movable relative to member 21 to provide parallel linkage movement for the anode bars 20 so that the width of the anode 11 can be adjusted to accommodate lengths of strip of different widths. As shown in Figure 1, when member 23 is moved from the position shown in full lines to the position shown in broken lines, the anode bars 20 are swung about the axes of pins 22 and the width of the anode is reduced. The anode bars 20 are disposed in a plane parallel to the path of the strip surface 12 and are movable about individual axes located in a plane normal to the plane of the strip surface.

A. spacing member 26, similar to member 23, extends across and beneath the opposite ends of the anodeY bars 20 and each bar is pivotally connected to the member 26 by a pin 28, similar to pin 24. lt will be noted that pin 28 needs to be rotatable relative to the bar or the member 26. The member 26 is movable relative to-member 2l and increases the stability of the anode bars, particularly during movement, and additionally aids in maintaining the bars 20 parallel.

Each member 23 and 26 is connetced to a member 30 and 31, respectively. The member 30 is provided with an electrical connecting member or bus bar 32 which isV adapted to be connected to a source of electric current and member 31 is provided with a similar connecting member or bus bar 33 for a similar purpose. The members 23, 24, 26 and 28 are electrically conductive and members 24 and 26 are electrically connected to bus bars 32 and 33, respectively. When bus bars 32 and 33 are connected to a source of electroplating current, both ends of cach bar 20 are ocnnected to this source. Preferably, either both ends or the middle portion of each anode bar 20 is connected to a source of electroplating current to obtain more uniform distribution of the current density. i

The cell 10 includes power actuated means for adjusting the width of anode 11. There is a long lead screw 35 rotatably mounted on the side of tank 18. This screw carries a nut 36 and is connected` to a motor 37 which upon energization rotates lead screw 35 to move the nut 36 along the screw. The motor 37 is reversible and the nut can be moved along the screw in either direction. Nut 36 is connected by link 38 to member 23 so that rotation of screw 35 varies the width of anode 11. The anode 11 is widened or narrowed, depending upon the direction of rotation of motor 37 andy screw 35 which in turn controls the direction of movement of member 23.

The cell is movable back and forth in a direction transverse to the path of the strip and in a plane parallel to the strip surface. Beneath tank 18, there are a pair of rails 40 mounted on a supporting framework 4l. The tank 18 carries flanged wheels 42 mounted on rails 4G. A reversible motor 44 is mounted on the framework 41 and con; c l to a long lead screw 45 which is engaged by a nut rotatably mounted on a bracket 47 connected to the bottom of tank 18. When motor 44 is energized, the lead screw 45 is turned and tank 18 and anode 1l are moved across the path of the strip in a plane parallel to the strip surface. The direction of movement depends on the direction of motor rotation.

The electroplating line includes a control circuit for motors 37 and 44 for varying the width of the anode 10 in accordance with the width of the strip being plated and for moving the anode across the path of the strip to maintain the anode in alignment with the strip. Referring to Figures 5 and 6, a direct current generator for supplying plating current to cell 10 is indicated at 50 with a lead wire 51 going to the bus bar connections 32, 33 of the anode support and a lead 52 going to the contact roll 15. A source of electrical power, such as 200 volt or 440 volt alternating current lines are shown at 53 and 54. These power lines are connected by means of conductors 55 and 56 to a control box A, and by conductors 57 and 58 to a control box B. Power lines 59 and 60 lead from control box A to the motor 44, shown in Figure 3. Power lines 62 and 64 lead from control box B to motor 37.

A source of high frequency energy, for example, 10,000 cycles per second, is shown at 66 with a lead 67 going to the contact roll 15 and a lead 68 going to control box A. The voltage across the high frequency generator is to be applied at two points in control box A, so conductor 68 is shown divided into conductors 69 and 70. Conductors 69 and 70 pass through control box A and by means of conductors 71 and 72 pass to control box B. Conductors 71 and 72 pass through control box B and by means of conductors 73 and 74 are connected to a pair of rubber covered condenser plates 75 and 76, respectively, mounted on tray 18 by brackets 77 and 78 on opposite sides of the path of the strip S.

Within control box A, conventional electrical apparatus is arranged such that current in power lines 59 and 60 applied to motor 44 is controlled in accordance with the relative value of current in conductors 69 and 70. For example, if the current is equal in conductors 69 and 70, no current will be flowing in power lines 59 and 60 and, therefore, motor 44 will not be actuated. If the current in conductor increases over that in conductor 69, motor 44` will operate in one direction. lf current in conductor 69 is greater than in conductor 70, motor 44 will operate in the other direction. By this means, the capacitance of each of the condensers formed by the strip S and plates and 76 in the circuits including the high frequency generator 66, the contact roll 15 and the strip S will control the operation of motor 44 to move the tray 18. lf more current flows from the strip to plate 75 due to there being a larger area of strip opposed to this plate, the motor 44 is connected so as to move the tray 18 and both plates 75 and 76 until equal areas of the plates are opposed to the strip.

Controller B includes conventional electrical equipment which, by the amplitude of the current in high frequency conductors 73 and 74 will control the current in power p lines 62 and 64. Thus, if large areas of plates 76l and 75 are opposed to strip S passing through the line or, in other words, ifthe strip is wide, a large amount of high frequency current will pass through conductors 73 and 74. The control apparatus in control box B is of suchr Y Referring to Figure v7, vstrip responsive solenoids 81 and 82 are used in place of strip responsive plates 75 and 76 to control the amount of current in an auxiliary circuit, such as that generated by the high frequency vgenerator 66 in Figure 5. The amount of current flowing through a solenoid or choke coil is determined by the position of its associated core 83 or 84 which, in turn, depends upon the width or position of the strip. The amplitude of the currents in the auxiliary circuit controls the movements of the tray 18 and the anode 10- as in Fig# ure 5. Y

Referring to Figure S which shows a modified control circuit for adjusting the width of anode 18 in response to variations in strip width and formoving and maintaining the anode in alignment with the strip upon lateral movement of the strip, power lines 86 and 87 are con-` nected to a suitable source of electric current. Control boxes similar to control boxes A and B are indicated at C and D. Electric lights 88 and 89 are disposed along opposite edges of the path of the strip, and each light is connected by wires 90 and 91 to lines 86 and 87. Strip responsive photoelectric cells are indicated at 93 and 94, and each cell has a relatively large area of light reception. Thecells 93 and 94- are disposed opposite to lights 88 and 89, respectively. 1 In this modification, control boxes C .and D are operated in accordance with the currents generated in photoelectric cells 93 and 94. If the strip tends to weave, one photoelectric cell has its light reduced and the other photoelectric cell has its light increased. Control box C, like control box A, then supplies current to motor 44 to energize the motor and rotate screw 45 to move the anode into alignment with the strip.

forth and oftenV does not move along a lxed straight path.

As shown in Figure 4, which is somewhat exaggeratedfor purposes of illustrationgthe strips will move along a path as shown in full lines, and then will move laterally to the path shown in broken lines. This weaving back and forth of the strip may be continuous or intermittent. Heretofore,. it has been customary, to make the anode wider than the strip and as wide as the path covered by the weaving strip, Thisis wasteful of anode metal, causes operational dilhculties and results in the deposit of excess metal along the edge portions of the strip. In accordance with the present invention, the control circuit includes means operable upon lateral movement of the strip for energizing motor 44 to moveA the anode 11 into alignment with thestrip. moves laterally from the position shown in full lines to the position shown in broken lines in Figure 4, then the 'capacitance of condenser plate 75v is increased relative to that of plate 76,lor the cores-'83 and 84 will be moved to increase the current owing through solenoid 81 and decrease the current flowingV through solenoid 82 or the amount of light reaching cell 93. will be increased and the amount of light reaching cell 94 will be decreased. Upon the occurrence of any one of these conditions, motor 44 is energized to move tank 18 into alignment with strip S. If the strip moves laterally in the'opposite direction, the

opposite effect is produced by the control circuit andv motor 44 is energized to move the cell in the opposite direction into alignment with the strip.

Frequently, successive lengths of the strip will be of dilferent widths with some lengths narrower or wider than others. 'Customarily,' the anode has, in the past, been made wide enough to accommodate the strip of greatest width and the same anode is then used for the narrower :lengths ofv strip. This also causes operational diliiculties,

wastes anode metal, and causes an excessive deposit of anode metal along the'edges of the strip. In accordance with the present invention, the control circuit includes means for energizing themotor 37 in response to a change If the width of the strip changes, becomes wider or narrower, more or less light isI transmitted equally to both photoelectric cells 93 and 94, and a current kproportional to this change is transmitted through conductors 96 and 97 to control box D, which then imparts a measured amount of power to motor 37 to adjust the anode width in accordance with the strip width. There is a limitation on the amount of anode width control for any given position of the photoelectric cells as a result of the limitation on the width of the area each cell can scan.

The electroplating line is operated continuously and the strip is continuously and progressively moved across the electroplating cells in contact with the bath of electroplating solution in the tank of each cell. Electroplating solution is continuously supplied to each tank. Each tank 18 is provided with an inlet tube 99 connected through a pipe or conduit 100 to a pumping system, not shown. Between the cells 10, there are pans 101 for collecting the overflowing solution and the solution dragged out of the tanks by the moving strip. This solution is returned to a central collector tank, not shown, replenished if necessary and then returned to the cells by the pumping system. The means for circulating the electrolyte solution forms no part of the presentinvention and the circulating or pumping system may be of a type customarily used for electroplating lines.

When continuously electroplating strip metal, such as steel strip, the moving strip weaves laterally back and in strip width for varying the width of the anode in accordance with the width of the strip.

vInoperatiomthe strip is continuously moved along the line across the electroplating cells.

relatively narrow, the capacitance of condenser plates 75 l `and 76 will be decreased or the position of cores 83 and 84 will change to reduce the current flowing through the solenoids, or the amount of light reaching the photoelectric cells will increase and each of these conditions will result in energization of motor 37 and cause the nut 36 to move inwardly along screw 35 to the position shown in broken lines. This causes parallelogram movement of the anodebars 20 about the axes of pins 22 to reduce the width of anode ,11. lf the next length of strip is wider, the effect is reversed and the motor 37 is energized to move nut 36 out along screw 35 to widen the anode. Thus, the width of the anode is automatically adjusted and maintained in correct relationship to the strip.

The presentl apparatus is primarily intended for plating strip steel, such as black plate, with a coating of protective metal such as tin, but the apparatus may be used for plating other strip metal with coating of other metal or metals.

I claim:

l. Apparatus for progressively electroplating a surface of successive lengths of strip of the same and dilferent If, for example, the strip S weaves or The anode has a maxi-v mum width equal to or greater than the widest strip to 1? for connecting the anode and the ,fstrip to a source of electroplating. current as 4anode and cathode, respectively, anode supporting and .spacing means supporting theanode elements in the tank means withV the anode elements extending transversely of and from side to'side of the path of the strip in spaced lapart parallel relationship, the anode elements being rotatable about individual axes located in a plane normal to the path of the strip, said plane being parallel to the ldirection of strip travel, the supporting and spacing means including movable means engaging the anode elements and being movable in opposite directions parallel to the direction of strip travel for rotating the anode elements-about the axes to varythe width of the anode while maintaining the anode velements parallel, a reversible electric motor carried by the tank means and connected to the rmovable means and operable upon energization to move 4the `movable means in either opposite direction, an electric circuit means for connecting the motor to a source of electric current, and control means interposed in the circuit means for controlling the operation and direction of Arotation of the motor, said control means including a irst sensing means positioned along one side of the tank means inthe region of one side of the path of the strip, a second sensing means positioned along the other side of the tank means in the region of the path of the other side of the strip, the rst and the second sensing means extending from the respective sides of the tank means a substantial distance transversely inwardly beyond respective sides of the path of the strip, the first and second sensing means being operable to produce control signals responsively to the degree the sensing means overlie respective sides of the'path of the strip, and means operable responsively to the control signals produced by the first and second sensing means for controlling the electric circuit means whereby the movable means are moved in a direction to increase or decrease the Width of the anode responsively to a decrease or an increase in the width of the paths of the strip,

2. Apparatus for progressively electroplating a surface of successive lengths of strip of the same and different widths, the apparatus comprising tank means including means for containing a bath of electroplating solution,

means for longitudinally moving the strip along a path across the tank means with the surface to be electroplated in lcontact with the solution in the tank means, an anode comprising a plurality -of elongated anode elements, means for connecting the anode and the strip to a source of electroplat-ing current as'anode and cathode respectively, anode supporting and spacing means supporting the anode element inthe tank means with the anode elements extending `transversely of and from side to side of the path of the strip is spaced apart parallel relationship, the anode elements being rotatable about individual axes located in a plane lnormal to the path of the strip, said plane being parallel to the direction of strip travel, the supporting and spacing means including movable means engaging the anode elements and being movable in 'opposite directions parallel to the direction `or strip travel for rotating the anode elements about the axes to vary the width of the anode while maintaining the anode elements parallel, a reversible electric motor `carried by the tank means and -connected to the movable means and operable to move the tank means in either opposite direction, an electric circuit means for connecting the motor to a source of electric current, and control means interposed in the circuit means for controlling the operation and direction of rotation of the electric motor, said control means including a first condenser plate disposed along one side of the path of the strip, a second condenser plate disposed along the other side of the pa'th of the strip, each of the condenser plates forming a condenser with the strip in which the lateral position of the strip relative to the condenser plates determines the capacitance `of each condenser, and means operative responsively to the capacitance of the condenser for con trolling vthe electric motor.

References Cited in the le of this patent UNITED STATES PATENTS 

1. APPARATUS FOR PROGRESSIVELY ELECTROPLATING A SURFACE OF SUCCESSIVE LENGTHS OF STRIP OF THE SAME AND DIFFERENT WIDTHS, THE APPARATUS COMPRISING TANK MEANS INCLUDING MEANS FOR CONTAINING A BATH OF ELECTROPLATING SOLUTION, MEANS FOR LONGITUDINALLY MOVING THE STRIP ALONG A PATH ACROSS THE TANK MEANS WITH THE SURFACE TO BE ELECTROPLATED IN CONTACT WITH THE SOLUTION IN THE TANK MEANS, AN ANODE COMPRISING A PLURALITY OF ELONGATED ANODE ELEMENTS, MEANS FOR CONNECTING THE ANODE AND THE STRIP TO A SOURCE OF ELECTROPLATING CURRENT AS ANODE AND CATHODE, RESPECTIVELY, ANODE SUPPORTING AND SPACING MEANS SUPPORTING THE ANODE ELEMENTS IN THE TANK MEANS WITH THE ANODE ELEMENTS EXTENDING TRANSVERSELY OF AND FROM SIDE TO SIDE OF THE PATH OF THE STRIP IN SPACED APART PARALLEL RELATIONSHIP, THE ANODE ELEMENTS BEING ROTATABLE ABOUT INDIVIDUAL AXES LOCATED IN A PLANE NORMAL TO THE PATH OF THE STRIP, SAID PLANE BEING PARALLEL TO THE DIRECTION OF STRIP TRAVEL, THE SUPPORTING AND SPACING MEANS INCLUDING MOVABLE MEANS ENGAGING THE ANODE ELEMENTS AND BEING MOVABLE IN OPPOSITE DIRECTIONS PARALLEL TO THE DIRECTION OF STRIP TRAVEL FOR ROTATING THE ANODE ELEMENTS ABOUT THE AXES TO VARY THE WIDTH OF THE ANODE WHILE MAINTAINING THE ANODE ELEMENTS PARALLEL, A REVERSIBLE ELECTRIC MOTOR CARRIED BY THE TANK MEANS AND CONNECTED TO THE MOVABLE MEANS AND OPERABLE UPON ENERGIZATION TO MOVE THE MOVABLE MEANS IN EITHER OPPOSITE DIRECTION, AN ELECTRIC CIRCUIT MEANS FOR CONNECTING THE MOTOR TO A SOURCE OF ELECTRIC CURRENT, AND CONTROL MEANS INTERPOSED IN THE CIRCUIT MEANS FOR CONTROLLING THE OPERATION AND DIRECTION OF ROTATION OF THE MOTOR, SAID CONTROL MEANS INCLUDING A FIRST SENSING MEANS POSITIONED ALONG ONE SIDE OF THE TANK MEANS IN THE REGION OF ONE SIDE OF THE PATH OF THE STRIP, A SECOND SENSING MEANS POSITIONED ALONG THE OTHER SIDE OF THE TANK MEANS IN THE REGION OF THE PATH OF THE OTHER SIDE OF THE STRIP, THE FIRST AND THE SECOND SENSING MEANS EXTENDING FROM THE RESPECTIVE SIDES OF THE TANK MEANS A SUBSTANTIAL DISTANCE TRANSVERSELY INWARDLY BEYOND RESPECTIVE SIDES OF THE PATH OF THE STRIP, THE FIRST AND SECOND SENSING MEANS BEING OPERABLE TO PRODUCE CONTROL SIGNALS RESPONSIVELY TO THE DEGREE THE SENSING MEANS OVERLIE RESPECTIVE SIDES OF THE PATH OF THE STRIP, AND MEANS OPERABLE RESPONSIVELY TO THE CONTROL SIGNALS PRODUCED BY THE FIRST AND SECOND SENSING MEANS FOR CONTROLLING THE ELECTRIC CIRCUIT MEANS WHEREBY THE MOVABLE MEANS ARE MOVED IN A DIRECTION TO INCREASE OR DECREASE THE WIDTH OF THE ANODE RESPONSIVELY TO A DECREASE OR AN INCREASE IN THE WIDTH OF THE PATHS OF THE STRIP. 